A couple of articles I came across on postal history
Neither snow nor rain nor heat... A history of the U.S. Postal Service
The U.S. Postal Service was one of our earliest experiments in democracy. The vast transportation networks that led to more than 30,000 post offices remain at the heart of many communities and still reach into the most remote parts of our country. This hour on The Colin McEnroe Show, a look at the past and the future of the post office.
The Postal Service Begins
Benjamin Franklin served as postmaster general until his diplomatic mission to France in November 1776. He was in office when the Declaration of Independence created the United States in July 1776, which made Franklin the first Postmaster General of the United States. America’s present Postal Service traces its origins to the system Franklin initiated.